I have lens cells that need a working Alphax/Betax 3 and one thing I've found is that these shutters aren't all identical the rear part with the lens mounting threads can be different and this significantly affects the lens spacing by 5 or 6mm. So you need the right combination of lens/shutter.

I want to keep my ceels because ihave shutters to repair so want to keep my cells, you might try looking for Velostigmat/Raptar 6", Series IIIa EWA f12.5 10x8, or Turner Reich 5x8 cells they all fit, but you'll need to see what aperture scale you have, and probably make a new one.